Pump



Jan. 17, 1933. J. E. HOLVECK PUMP Filed June 27, 1931 3 Sheets-Sheet lINVENTOR NOLLDOS Jan. 17, 1933.

J. E. HOLVECK PUMP Filed June 27, 1931 3 Sheets-Sheet 2 EN \w x .L 4 w RQM INVENTOR Jan. 17, 1933. J. E. HOLVECK 1,394,869

PUMP

Filed June 27, 1931 3 Sheets-Sheet 3 Patented Jan. 17, 1933 UNITEDSTATES PATENT OFFICE JOSEPH E. HOLVECK, OF PITTSBURGH, PENNSYLVANIA PUMPApplication filed June 27,

This invention relates to pumps or compressors, and more particularly toprocedure and mechanisms for loading and unloading such apparatus. Theinvention specifically relates to the loading and unloading of pumps 01'compressors having reciprocating pistons.

The object of my invention is to produce a procedure and a mechanism forloading and unloading pumps which are simpler and more effective thanthose now in use and known to me.

A further object is to produce a loading and unloading mechanism whichis so arranged that the torque on the drive shaft will be more or lessgradually increasedas the pump is loaded and will be decreased as thepump is unloaded.

These and other objects, which will be made more apparent throughout thefurther gradually description of the invention, are accomplished bymeans of mechanisms embodying the fe-atureshcrein described, andillustrated in the drawings accompanying and forming part hereof. I

In the drawings, Figure 1 is a view partially in section of apparatusembodying my invention. The figure includes a sectional view of thesuction chamber of a compressor or pump, such as is here involved. Fig.2 is a fragmental sectional view along the line .22 of Fig. l, thehousing for the shaft illustrated being omitted for convenience ofillustration. Fig. 3 is a sectional view along the line 3-8 of Fig. 1,showing the inlet or suction valve in place in the delivery port of thesuction chamber. Fig. 4 is a diagrammatic view illustrating therelationship between the crank shaft of the pump and cams forming a partof the unloading mechanism. Fig. 5 is a partial end view of a pump, aportion being shown in section, and illustrates means for motivating theloading and unloading mechanism. Fig. 6 is a fragmental Viewillustrating. a modified arrangement of the motivating means. Fig. 7 isa diagram illustrating graphically the angular relation of the dischargeand suction strokes of a single acting triplex pump. Fig. 7a is, ineffect, a continuation of Fig. 7, and illus- 1931. Serial No. 547,301.

trates the relative positions of the operating cams when the cylindersof a triplex single acting pump are unloaded. Fig. 7 b shows therelative positions of such cams when the pump is loaded. Fig. 7c is, ineffect, a continuation of Figs. 7a and 7b, and shows the relativepositions of the crank pins at the beginning (upper View) and at the end(lower view) of a loading or unloading operation, and Fig. 8 is a viewillustrating graphically the effect of the loading and unloadingoperation of a single acting triple pump.

Throughout the further description I will employ the term pump toinclude either a compressor or a pump, the understanding, however, beingthat the term, as herein employed, is limited to include onlycompressors or pumps having cylinders and reciprocating pistonsoperating therein. P

In a great many installations of pumps it is customary to drive the pumpcontinuously and to employ some mechanism for automatically unloadingthe pump when a desired degree of pressure has been obtained, or whenthe desired amount of fluid has been delivered by the pump to anaccumulator. It is also customary to contemplate automatic reloading ofthe pump. In my Patents 1,316,79 of September 23, 1919 and 1,528,547 ofMarch 3, 1925 I have illustrated and described mechanisms for unloadingand loading pumps so that the pump may be continuously operated evenunder widely varying load conditions. My present invention rer latesbroadly to loading and unloading mechanisms such as are covered by myabove mentioned patents, but specifically to the particular mechanismhere illustrated and the particular procedure here described for loadingand unloading the pump. I have not illustrated a complete pump, nor haveI illustrated the accumulator or other device for receiving the fluid orliquid pumped, since I have deemed it unnecessary to so complicate thepresent disclosure and since pumps of the type here involved are wellknown and their operation well understood. For the same reason I havenot illustrated accumulators or other apparatus for receiving the pumpedfluid.

For the purpose of simplifying the further description of my invention Iwill briefly describe what I mean by the term pump cycle. Ordinarily theinlet valve to eac pump cylinder-whether the pump is a single ormulti-cylinder pump'or is a single acting or' double acting pump-is asuction actuated valve; that is to say the inlet valve opens in responseto the diiierence in pres sure of the fluid or liquid moving toward thecylinder and the pressure within the cylinder, and this'difierence inpressure is occasioned by the fact that the pump piston moving away fromthe inlet port of thecylinder tends to create a vacuum within thecylinder and thereby in effect sucks the fluid or liquid from the socalled suction chamher into the cylinder. The inlet valve, having openedin response to the conditions above described, remains open as long asthere is a flow of liquid or fluid from the suction chamber into thecylinder, and then closes. From the above it will be apparent that theinlet valve is in efiect a check valve in that it permits a flow throughthe inlet port to the cylinder, in one directioni. e.,

toward the cylinder but prevents a flow inthe opposite direction andremains closed as long as the pressure within the cylinder exceeds thepressure within the suction chamber. The pump cycle for each cylinderand its cooperating piston is completed by each full reciprocatiou'ofthe piston, or for each complete revolution of the crank which initiatesand completes the suction stroke of the piston in question, and theninitiates and completes the discharge stroke of that piston. To furtherdefine my meaning of the term pump cycle it may be said that in a singleacting pump, the pump cycle starts, for each individual cylinder, as thepiston contained within the cylinder starts to move away from the inletend of the cylinder. Throughout this movement of the piston the cylinderis in effect drawing in a charge of liquid or fluid, and the piston ismoving through what has been termed the suction stroke. The piston thencomes to rest, it may be for an infinitesimal period of time, and thenmoves in the reverse direction or back toward its original position,thereby discharging, through the discharge port of the cylinder, theliquid trappedin the cylinder by the closing of the inlet valve at theend of the suction stroke. The discharge port is, of course, providedwith an appropriate valve, which like the inlet valve, is ordinarily apressure responsive and a one way valve. At the end of this returnmovement of the piston, it momentarily comes to rest, and the pump cycleis completed, since the next movement of the piston will again tend tocreate a vacuum within the cylinder and thereby occasion the opening ofthe inlet Lacuna valve and a flow of liquid from the suction chamberinto the cylinder.

As in my previous patents, the loading and unloading mechanism effectsthe operation of the inlet valves of the various cylinders of the pumpand each cylinder is unloaded by preventin its inlet valve from closingat the end 0? the suction stroke. Under such conditions fluid drawn intothe cylinder by the suction stroke of the associated piston is nottrapped, consequently, the return stroke of the piston, instead ofcompleting the pump cycle, merely forces the fluid back through the openinlet port and into the suction chamber with the result that thedischarge valve of the cylinder does not open, and the pressure of thefluid-is not increased above the fluid pressure within the suctionchamber. That is to say, no effective work is done on the fluid by theparticular piston and cylinder involved. As pointed out in my previouspatents the unloading operation is accomplished so as to graduallydecrease the torque on the shaft.

As described in my revious patents the mechanism for accomplishing theunloading of the pump is so arranged that the cylinders of amulti-cylinder pump are successively unloaded, that is to say, thecylinders are unloaded one after the other. My present invention relatesto mechanism for accomplishing this and also for accomplishing areloadin g of the cylinders so as to gradually increase the torque onthe drive shaft of the pump, and in such a way as to prevent a partialloading of any cylinder and the resulting detrimental effect which wouldbe occasioned by -water hammer in case of a hydraulic pump.

In other words, the loading operation is rendered effective for eachindividual cylinder only at a particular point in the pump cycle, and atsuch point as'will prevent a partial loading of any cylinder and insurea gradual increase of the load from substantially zero torque to maximumtorque.

The apparatus here illustrated is primarily adapted to be automaticallycontrolled, i. e., by variations in the level of the fluid pumped, or bythe pressure resulting from the pumping operation or by both the fluidlevel and the resulting pressure. For example, where the pump deliversfluid to a hydrostatic accumulator the pumping operation may becontrolled by variations in the level of the fluid within theaccumulator or by the pneumatic pressure within the accumulator or itmay be controlled by a combination of the fluid level and pneumaticpressure within the accumulator. It will, of course, be apparent thatwhere a multi-cylinder pump is employed a change in condition which willeffect the control of the pump may occur at any time during the pumpcycle of any one of the cylinders and in order to properly load andunload the pump it is therefore necessary to control the'automaticregulation so that it is rendered effective, either to load or unloadthe various cylinders, at the proper time during the pump cycle of eachcylinder. It is, of course, apparent that a separate loading andunloading mechanism maybe employed in connection with each cylinder, andthat all of these individual mechanisms may respond either to individualautomatic means 10 or to a single automatic means, which, as stated, isrseponsive tothe variations of fluid level or pressure, or both, withinthe accumulater.

For the sake of simplicity and to reduce 16 the cost of equipment Iemploy a single mechanism which is so arranged that it accomplishes theloading and unloadng of all the cylinders of a multi-cylinder pump andaccomplishes this in such a way as to gradually 20 increase the torqueon the drive shaft of the pump during the loading operation, and togradually decrease the torque during the unloading operation. Themechanism illustrated in the drawings is provided with cam operatedfingers which, during the unloading operation, cooperate with the inletor suction valve of the various cylinders to prevent those Valves frommoving to close the inlet ports. In this way each finger, Whenrenderedoperative as a part of the unloading mechanism, prevents the completionof th e pump cycle in the cylinder with wh ch it is associated. On theother hand, during the loading operat on the fingers move automaticallyin response to a change of condition so that each inlet valve isrelieved of the restraining effect of the finger and is permitted tomove to close the inlet port in response to the forces acting on thevalve.

One of the features of my invention is, therefore, to provide simplemechanisms which will synchronize the loading and unloadingoperationsinitiated by automatic means responding to the above mentionedchanges in conditions-wit-h the pump cycles in the individual cylinders,so that each operationi. e. loading or unloading-4s accomplished at thedesired point in each pump cycle. That is to sav, my inventioncontemplates a simple mechanism which responds to automatic control, butwh ch will load or unload each cylinder at the proper point during thepump cycle of that cylinder and which will thereby more or lessgradually increase the torque on the drive shaft of the pump during theloading operation and more or less gradually decrease it during theunloading operation.

I have illustrated the mechanisms here disclosed as embodying myinvention, as applied to a single acting triplex pump. The furtherdescription, however, will disclose to those skilled in the art how theinvention may be employed in connection with any multi-cylin- 65 derpump whether double or single acting.

In Fig. 1 the apparatus illustrated is associated with a solenoid 7,which, through the agency of mechanisms not here involved and not shown,is automatically energized and deenergized in response to variations inconditions such as level of the liquid pumped or accumulator pressure orboth. I have assumed that when the conditions are such as to make itnecessary to unload .the pump the solenoid 7 is (lo-energized, therebypermitting its armature 7a to move downwardly in response to gravity asaugmented by the weight 7 b. This movement of the armature actuates abell crank 8, which in turn shifts or tends to shift the position of adetent actuating rod 9, through the agency of a finger 8a, which formsone arm of the bell crank. Y It will, of course, be understood that thefinger is bifurcated at its end or otherwise interlocked with the rod 9so that it is capable of shifting the rod 9one way or the other,dependent upon the direction of the movement of the armature 7a. The rod9 extends into an axial opening in a shaft 10 on which a pinion 11 is somounted as to turn freely thereon. Any suitable, well known means may beemployed for preventing the gear from moving longitudinally withrelation to the shaft 10. This shaft is shown operatively connected to ashaft 12 by means of a coupling 12a. The shaft 12 projects into thesuction chamber 13 of a pump (not shown) and is provided with cams 14,14 and 14", which effect the loading and unloading operations bycooperating with the inletvalves associated with the various cylindersof the pump.

' As shown in Fig. 3, the suction chamber is provided with three ports,each of which is adapted to receive an inlet valve 37 for one of thepump cylinders. As there illustrated, each inlet valve is yieldinglyheld against its seat or in the closed position by means of a spring 38,and is enclosed within a suitable housing 36. Each of the cams 14, 14',and 14 is associated with a finger 41, which is pivotally mounted on apin 42 carried by the casing of the suction chamber 13 and isoperatively associated with a pin 39, guided by a way 40, which issupported by a spider 40a spanning the port of the suction chamber. Therod 39 is slidable through the way 40 and is screw'threaded at its upperend so as to provide for-a cap 39a which is screwed thereon and istherefore capable of being adjusted for the purpose of increasing ordecreasing the effective length of the rod 39. The lower end of the rodrests on the finger 41 and is axially aligned with the stem of the inletvalve 37 so that when the finger is lifted by the associated cam (14)thecap 39a or the upper end of the rod prevents the valve -37 frommoving to a closed position. The

cam 14, like the other two cams designated by related referencenumerals, is rigidly secured in place on the shaft 12 and each such camis so arranged that it supports the free end of the associated fin er 41and thereby supports the associatethro 39.

In Fig. 7a I have shown the. cams in the positions they occupy while thepump is un-' loaded. Fig. 7 b shows the positions of the cams when thepump is loaded. It will be noted that the cams are all of similarcontour, but that they are so placed on the "shaft 12 that their lobesmove into and out of cooperative relation with the associated fingers 41at different times during the rotation of the shaft 12. The shaft isrotated by means of the pinion 11, which, as has been said, is rotatablymounted on the shaft 10. Figs. 7a and 7?) make it apparent that arotation of the shaft 12 through an arc of approximately 180degrees-,will shift the cams from the loading to the unloading position(Fig.

7a) or from the unloading to the loading position (Fig. 7b).

In order that this shifting of the cams may take place at the properpoint during the cycle of operation of the pump, the pinion 11 isactuated-in synchronisin with the rotation of the crank shaft of thepump. In the illustrated embodiment of the invention I have shown meansfor oscillating the pinion through an arc of about 180. degrees, and asillustrated in Fig. 5 the pinion moves through both swings or phasesofits oscillatory movement, once during each revolution of 'the driveshaft-i. e., crank shaftof the pump. As shown, a crank disc ll?) ismounted on the end of the crank shaft 46 of the pump adjacent theflywheel 47. This disc carries a pin 48 on which a connecting rod 44 isjournaled. The lower end of the connecting rod carries a rack 44a, whichmeshes with the pinion 11. As shown in Fig. 5, the rack ll may be heldin meshing engagement with the pinion by means of a roller 45, which issuitably journaled on the housing 43 of the pinion. If desired, the rackmay be adjustably mounted on the connecting rod so as to facilitate thepositioning of the pinion with relation to the shaft 10 and the detentscarried thereby. I have shown a simple and well known form of such anadjustment at 440.

With the arrangementillustrated i:. will be apparent that the pinionoscillates about the shaft 10 as the crank shaft rotates. and, as hasbeen said, it first moves through about 180 degrees in one direction andthen back in the opposite direction to its original position, and thatboth these movements take place during a revolution of the crank shaft,

or. more properly siated. during one complete cycleof the multi-cylinderpump. It is, therefore, apparent that the pinion starts its oscillatorycycle at a particular time during each revolution of the crank shaft,or, more strictly speaking, at a particular time during the completecycle of operation of the nausea v pump. I employthis oscillating pinionto render the movements of the automatically responsive device (thearmature effective edge so that the jaw gradually increases in 7 width.circumferentially of the pinion, toward its detent-engaging-face. Theshaft 10, besides receiving the rod 9, is slotted asat 15 to receive andguide the detents 10a and 10?). These detents are located on oppositesides of the pinion and 180 degrees apart with relation to the shaft 10.As shown, each detent extends through a suitable aperture provided inthe rod 9 and they are so located that when the rod is moved to itsinner position, as shown in Fig. 1, the detent 10b is in position to beengaged by the jaw 11?), whereas the detent 10a is moved, longitudinallyof the shaft 10, to such a position that it clears the jaw 110.. usingthe oscillations of the pinion. The arrangement is also such that whenthe rod 9 s moved to its outermost positon by the bell crank 8, thedetent 10a is moved to position to be engaged by the jaw 11a..whereasthe detent 10b is moved to such the rod 9 and the shaft 10 by a ring 16which engages the detent and encircles the shaft, but which permits freemovement of the detent along the shaft and in the slots 15. Each ring isheld in place on its corresponding detent by a set screw 16a.

Assume that a change in conditions has been encountered wh ch occasionsa movement of the automatic control mechanism (armature 7a) to theposition shown in Fig. 1. Under such conditions the detent 10b is movedinto the path of travel of the jaw 11?) with the result that the detentis picked up by the jaw as it starts its oscillatory movement with 1 hepinion and consequently moves with the pinion throughout one phase ofthe pinion movement. This turnsthe shafts 10 and 12 and the cams 14,14', and 14" through 180 degrees. The next phase of the pinion movementcauses the jaw 11?) to move back away from the detent- 10?) and sincethe pinion 11 is free to rotate on the shaft 10 the subsequentoscillations of the pinion therefore do not affect or change theposition of either of the shafts 10 or 12. f If now, the conditionscontrolling the solenoid 7 change so that the energizing current of thesolenoid is interrupted, the armature 7a will drop, thereby moving therod 9 to its outermost position and moving the detent 10a into the lineof travel of the oscillating jaw 11a.

If this movement, or any'movement of the armature 7 41. takes placeafter the pinion has moved from its initial position the movement of thepinion will haveno effect on the detent in question, since that detentwill merely ride the bevel face of the associated jaw until such time asthe pinion returns to its initial position, when the detent will thendrop into place in front of the detent-engaging-face of the jaw and theshaft 10 will then be turned through 180 degrees and in the samedirection as the previous turning of the shaft. From this it will beapparent that both shafts 10 and 12 move as a unit and have but twofixed positions, which are 180 degrees apart. It will also be apparentthat each movement of the shaft 12, and consequently of the cams 14, 14and 14", takes place at a fixed point during the cycle of operation ofthe pump, or at a fixed point with relation to the pump cycle of eachindividual cylinder.

Fig. 7 is a diagram illustratin the pum piston movements durin theperiod that the pinion 11 moves on the first phasei. e., the

I operative phaseof its oscillatory motion and consequently during theperiod that a cam shifting operation takes place. Fig. 7a illustratesthe relative positions of the various cams 14 at the completion of thecam shifting operation wherein the cams are moved from the loading tothe unloading position. It will also be apparent that this viewincidentally illustrates the positions of the cams at the start of thecam shifting operation, which moves them from the unloading to theloading position. Fig. 7 b illustrates the positions of the cams at thecompletion of the cam shifting operation which moves them from theunloading to the loading position. The top view of Fig. 7 c illustratesthe positions of the crank pins A, B, and C of the pump crankshaft 46 atthe start of the first, or operative phase of the oscil latory motion ofthe pinion l1; and the bottom view illustrates the positions of thecrank pins as this phase of the pinion motion is completed.

It will be apparent from an inspection of these views that each cylinderis either loading or unloading during the operative phase of the pinionmovement. A reference to Figs. 7 and 7 c discloses that at the beginningof the operative phase of the pinion 11, the piston operating in thecylinder associated with the crank pin A and with the cam 14 is movingon its suction stroke and must move through 60 degrees of crank pintravel in order to complete that stroke. The cam 14 must therefore be sopositioned on the shaft and its operating lobe must be so proportionedthat it will position the parts (finger 41 and pin 39) to unload or loadthat cylinder as the piston completes the suction stroke and before itstarts on the discharge stroke.

This positioning of the cam and proportion-.

loading to the unloading position, or vice versa, must take place at theend of this stroke and prior to the beginning of the discharge stroke.The positioning and the proportioning of the cams 14 to accomplish thisis illustrated in Figs. 7a and 7b. The piston operating within thecylinder associated with the crank pin C and with which the cam 14" isassociated, is moving through the discharge stroke and must move through120 degrees of cran'k pin travel before the stroke is completed. It istherefore apparent that the loading or unloading operation initiated bythe pinion 11 must be deferred for 120 degrees of crank pin travel, andthe cam 14" is so positioned on the shaft 12 and is so proportioned asto its cam lobe to accomplish either the loading 'or the unloading atthe proper time during the stroke of the associated piston, i. e., atthe beginning of a suction stroke.

Fig. 8 is a diagram corresponding to Fig. 7, but graphicallyillustrating the effect of the loading or unloading operation in connection with a triplex pump. In this dia ram I have employed the sameletters, as in ig. 7, to designate the different curves which indicateconditions within the cylinders associated with the correspondinglylettered crank pins, diagrammatically illustrated in Figs. 7c. The lowerdiagram is a continuation of the upper diagram, but is shown as if anintervening portion between the two diagrams were omitted. The topportion of the view illustrates the effect of the unloading operation onthe various cylinders of the pump, whereas the bottom portionillustrates the eil'ect of the loading operation on the variouscylinders, and the two views together disclose the fact that theunloading cycle and the loading cycle each take place as the crank shaftmoves through approximately 180 degrees, and that the various pistonsoccupy the same relative positions at the beginning of the loading cycleas they do at the beginning of the unloading cycle. The curvesdesignated a, b, and 0 indicate suction stroke intakes; the curves a, band 0' illustrate discharge stroke displacements; and the curves (1, b"and 0"each of which is shown dotted-indicate unloaded strokedisplacements.

This combined chart discloses the fact that while the unloadingoperation is in effect accomplished during a particular 180 degrees ofcrank shaft travel, that it is in fact retroactive insofar as onecylinder of the pump is concerned. For example, the cylindercorresponding to the curve a is in effect unloaded at the beginning ofits suction stroke, since prior to the termination of that stroke itssuction valve is put under the restraint of the unloading mechanism withthe result that the cylinder does not load or does not pass, as innormal operation, from a suction to a discharge stroke. The piston, inmoving through what would normally be the discharge stroke, merelydisplaces the fluid drawn in by the preceding suction stroke as is shownby the curve a. The chart also discloses that, from the standpoint ofcrank shaft torque, the unloading is in effect accomplished on onecylinder with the result that the load on the crank shaft graduallydecreases from maximum to minimum torque. The particular cylinder inquestion is the one corresponding to the curve (*0 of the upper view.The cylinder corresponding to the curve bb completes one pump cycle andstarts the next pump cycle, in that its piston draws in a charge, butprior to the completion of this ortion of the pump cycle the inlet valveoi that cylinder is restrained so that the next movement of thecorresponding iston merely displaces the water so drawn 1n, as shownbythe curve b", and does not force it through the discharge port of thecylinder. 4

The lower view also indicates that the loading operation is to someextent retroactive with relation to the operation of the loading andunloadingmechanism. That is to say, the cylinder corresponding to thecurve aa is receiving a charge at the time the loading and unloadingmechanism becomes effective. This portion of the pump cycle of thisparticular cylinder is completed and the inlet valve then closes,thereby leading the cylinder with the result that theload on the pumpgradually increases from minimum to maximum torque as the correspondingpiston moves through that portion of its stroke dur ing which itsmovement is accelerated. It will also be apparent that the cylindercorresponding to the curve bb is not loaded until after the piston inthe cylinder corresponding to aa, is moving through the deceleratingportion of its stroke, with the result that the gradually increasingtorque occasioned by the cylinder b?) is compensated for by thegradually decreasing torque occasioned by the cylinder aa', as itspiston decelerates. The chart also discloses that the cylindercorresponding to the curve 0-0 is in effect unloaded, so far as crankshaft torque is concerned, for 120 degreesafter the loading cycle of theloading and the unloading mechanism, is completed.

In connection with these Figs. 7-70, it must be remembered that thepinion starts each phase of its motion from rest and is graduallyaccelerated to its maximum speed of travel and then is graduallydecele'rated until it again comes to. rest. This is also important inconnection with the engagement of the pinion with one or the other ofthe detents 10a or .106, since'the shaft 10, and consequently the shaft12 starts from rest with the pinion and is first accelerated and thendecelerated as it moves to shift the cams, with the result that thefirst part of each cam motion is a gradually accelerated motion, whereasthe cam motion is gradually decelerated as the cams move to their finalposition.

I have stated that each phase of the pinions oscillatory motion isthrough an arc of approximately 180 degrees and I have found that withthe apparatus illustrated it is desirable that each throw or each phaseof the pinion movement should be through an arc of about 185 degrees inorder to provide the desired clearance.

In Fig. 6 I have illustrated a modification of the mechanism formotivating the pinion in that I have shown the connecting rod 44actuated by a gear driven eccentric 50. The eccentric pin 50', to whichthe connecting rod 44 is operatively connected, is, in effect, carriedby a gear 52 which is driven by a pinion 51 operatively coupled to thecrank shaft. The gear and pinion are so proportioned that the pinionmoves through two revolutions while the gear moves through onerevolution. With this arrangement the operative phase of the pinion 11extends through a complete revolution of the crank shaft, consequently alonger period of time, from the standpoint of crank shaft rotation, isobtained in which to load or unload the cylinders.

It will be apparent that the variation in conditions which initiates theloading or the unloading of the pump or, which in the presentembodiment, occasions the energizing or the de-energizing of thesolenoid 7, may take place at any time during the oscillatory motion ofthe pinion 11. That is to say, the rod 9 may tend to shift the positionof the de tents 10a and 10?) after the pinion 11 has started on what Ihave termed the first, or operative phase of its movement, or as thepinion 11 is moving back or is in the second phase of its movement. Itwill, however, be apparent that any such movement of the detents will beineffective, insofar as the cam shaft 12'is concerned, since thefriction (friction of rest) of that shaft and associated parts willresist any such movement, and the jaws 11a and 11?) are so designed thateach detent will merely ride on the inclined face of the associated jawuntil the jaw has moved to such a position that the detent is capable ofdropping in front of its detent-engaging face. It is the purpose ofensuring this one direction,

movement of the cams the cam shaft 12 may be equipped with a ratchet andpawl or a suitabledetent for preventing a reverse movement, althoughThave found that such a device is unnecessary.

I have found it convenient to enclose the inion 11 in a housing, such asillustrated in ig. 1, and to mount the solenoid 7 on a bracket formed onthe closure for the housing. 15 This, in effect, makes the pinion 11,and its associated apparatus, including the solenoid, a unit which maybe readily installed with any pump. With such an arrangement it is alsoconvenient to mount the shaft 10 in suitable bearin s carried by thehousing and to provide oi rings for sealing the joint between the shaftand the housing so that the shaft may be submerged or partiallysubmerged in a lubricating liquid. Any suitable means may be employedfor mounting the shaft 12, but it is desirable to provide the shaft withgaskets for preventing the leakage of liquid around the shaft andbetween it and the walls of the suction chamber 13.

While I have described what I now consider to be the preferredembodiment of my invention it will be apparent that various changes,additions and omissf ons may be made without departing from the spiritand scope of the invention as defined by the appended claims.

What I claim is: i i

1. The combination with a multi-cylinder pump having a suction chamberprovided with a series of inlet valves, one for each cylinder of thepump, of devices for holding said inlet valves open durng the operationof the pump, to thereby unload the pump, an instrumentality moving insynchronism with the cycle of operation of the pump, and means forrendering said instrumentality effective in moving all said devices toan inoperative position with relation to said inlet valves.

2. The combination with a multi-cylinder pump having a suction chamberprovided with a series of inlet valves, of a separate devicefor holdingthe inlet valve of each cylinder of the pump open during dischargeperiods of such cylinder to thereby unload the pump, an instrumentalitymoving in synchronism with the cycle of operation of the pump, and meansrendering sa'd instrumentality effective in moving all said devices torelease said inlet valves and to thereby load each cylinder of the pumpat thebeginning of the discharge stroke of each such cylinder.

3. The comb'nation with a multi-cylinder pump having a series of inletvalves, of an oscillatory member, means for oscillating said member insynchronism with the cycle of op- 65 eration of the pump, devicesforcontrolling of such valves, an oscillatory member operstrumentalityeifective in actuatingsaid cam the operation of saidinlet valves,.an'dmeans for rendering said oscillatory member eflective to actuatesaiddevices andload or'unload each cylinder of the pump.

4. The combina-tionwith a multicylinder pump, and its inlet valves, ofa-se arate device for controlling the operation 0 each such inlet valve,an instrumentalityoperating in synchronism with said pump foractuatingeach such device to load the corresponding 7 cylinder of the pump at theend of the suction stroke of the piston of such cylinder.

' 5. The combination with a pump having inlet valves, of means forcontrolling said valves to load and unload the pump, and aninstrumcntality operating in synchronism with the drive shaft of thepump to actuate saidmeans to load or unload the pump at predeterminedpoints in its cycle of operation.

6. The combination with a multi-cylinder pump having a series of inletvalves, of an instrlunentality operating in synchronism with the pumpshaft, a separate device for controlling each said inlet valve, andmeans actuated by said instrumentality for actuating each such device toload the corresponding pump cylinder at the beginning of the dischargestroke of thepiston of such cylinder.

7. The combination with a pump, of an oscillating instrumentality movingin synchronism with the cycle of operation of the pump, and meansactuated by said instruinentality for loading the pump at the beiginning of a discharge stroke.

8. The combination in a multi-cylinder pump, having a series of inletvalves, of a separate lifting finger for holding open each ated insynchronism with the cycle of operation of said pump and means forrendering said oscillating member effective to actuate said liftingfingers and to control the operati on of each inlet valve and unloadeach cylinder of the pump during a suction stroke of the piston of eachsuch cylinder.

9. The combination with a multi-cylinder pump and its inlet valves, of aseparate device for controlling each such valve to load and unload thecorresponding cylinder, and means operating in synchronism with thecycle of operation of the pump for actuating said devices to load eachcylinder of the pump at the beginning of the discharge stroke of thepiston of such pump.

10. Thecombination with a multi-cylinder pump having an inlet valveleading to each cylinder, of a separate device for controlling each suchvalve to load and unload the corresponding cylinder of the pump, acamshaft for operating each of said devices in timed relation, aninstrulnentality oscillated in synchronism with the cycle of operationof the pump, and means for rendering said inshaft to load each cylinderof the pump at the beginning'of the discharge stroke of the pump pistonoperating in such cylinder.

11. The combination with a multi-cylinder pump having an inlet valveleading to each cylinder of the pump, of a separate device forcontrolling the operation of each inlet valve to load and unload thecorresponding cylinder of the ump, a shaft having cams thereon foroperating each of said devices, an instrumentality oscillated in timedrelation with the cycle of operation of the pump, and means forrendering said instrumentality effective in actuating said cam shaft.

12. The combination with a multi-cylinder pump having a suction valveleading 'to each of the cylinders thereof, of a separate device forlifting each of said valves, a shaft having "a series of cams thereonfor operating each of said devices and means for oscillating said camshaft including a shaft connected to said cam shaft, a member freelymounted on said shaft, means for oscillating said member in timedrelation to the pump shaft and means for rendering said oscillatorymember effective to turn said shaft and the cam shaft connected thereto.

- 13. The combination with a multi-cylinder pump having an inlet valveleading to each of the cylinders thereof, of a lifting finger for eachof said valves, a cam shaft for actuating said lifting fingers, a shaftconnected to said cam shaft, a pinion freely mounted .on said lastmentioned shaftmeans for oscillating said pinion about said shaft insynchronism with the cycle of operation of the pump and means for makingsaid pinion effective to turn said shaft and associated cam shaft toload or unload said pump.

14. The combination with a multi-cylinder pump having a suction valvefor each of the cylinders thereof, of a shaft, a member rotatablymounted on said shaft, means for oscillating said member in timedrelation with the drive shaft of said pump, meansv for ren dering saidoscillatory member effective to turn said shaft, and means actuated bythe turning of said shaft for loading each cylinder of the pump at thebeginning of the discharge stroke.

15. The combination with a multi-cylinder pump having a suction valvefor each of the said oscillating member to make it e ective to turn saidcam shaft and load or unload the pump.

17. The combination with a multi-cylinder pump having a series of inletvalves, of a separate device for controlling the operation of each ofsuch valves, means for actuating each of said devices, an oscillatorymember, means for oscillating said member first in one direction andthen in the opposite directien during each cycle of operation of thepump, and means for rendering said oscillatory member effective tooperate said device actuating means and load or unload each cylinder ofthe pump.

18. The combination of a multi-cylinder pump having a suction chamberand an inletvalve for each cylinder of the pump, of a separate devicefor holding each of said valves open to unload the pump, and means foractuating each of said devices at the beginning of the suction stroke ineach cylinder, said means lncludlng a cam shaft having a series of camsthereon one for operating one of said devices, a shaft connected to saidcam shaft, :1 pinion mounted on said shaft and rosaid pinion through anarc of 180 in synchronism with the pump shaft and means associated withthe shaft for engaging said pinion to make it effective to turn said camshaft through an arc of 180, the cams on said cam shaft being disposedso that each time the cam shaft is turned 180 each of the devices willbe operated.

In testimony whereof, I have hereunto subscribed my name this 25th dayof June, 1931.

JOSEPH E. HOLVECK.

.tatable relative thereto means for oscillating

